The present invention relates to a magnetic disk apparatus, and in particular, it relates to a magnetic disk apparatus, equipped with a ramp load/unload mechanism therein, and a position control method for a magnetic head slider thereof.
In a magnetic disk apparatus, wherein a head slider mounted on a suspension assembly, building up a head arm, flies or floats on or above the surface of the disk, by means of an actuator mechanism, thereby writing data on the magnetic disk or reading the data from said disk, the above-mentioned head slider is landed on a save area of the disk surface, when being in non-operating condition; e.g., the disk stops the rotation thereof. Such a type of the magnetic disk drive apparatus, as was mentioned in the above, is called; by a CSS (Contact-Start-Stop) type disk drive apparatus, in general.
On a while in recent years, for fulfilling the requirement of high recoding density to the magnetic disk apparatus, it is necessary to reduce the flying height of the slider mentioned above. For that purpose, it is indispensable of using a smooth disk. However, in case of using such the smooth disk, a contacting area increases between the magnetic disk and the slider, and then the friction force also increases between the magnetic disk and the slider. For this reason, there occur problems, such as, starting is difficult, in particular, in a case when applying such the smooth disk into the CSS type disk drive mentioned above, for the purpose of achieving the high density in recording thereof, for example.
Then, conventionally, as a way of preventing the magnetic disk apparatus from coming into such the difficulty on starting due to the large friction force, in the case when applying such the smooth magnetic disk therein, but without using the CSS method mentioned above, there was developed a magnetic disk apparatus of using therein an L/UL (Load and Unload) method, wherein the slider is made to load and unload on the rotating magnetic disk.
The L/UL mechanism of the head comprises, for example, a suspension assembly for the head arm, and a head holder mechanism constructed with a ramp block, which is provided in the disk drive. Namely, when being unloaded, a slider tub of the floating head is supported on the ramp, which is fixed on a drive side in the vicinity of an outer periphery of the magnetic disk. However, when being loaded, the head arm is rotated, and the tub releases from an inclined plane or slope of the ramp while moving and sliding on a tub holder surface thereof; thereby loading the head slider on the rotating magnetic disk. On the other hand, when being unloaded, the head slider is unloaded with conducting the reverse operation thereof; e.g., first of all, the tub contacts on the slope of the ramp and reaches to the tub holder surface while moving on that slope, slidingly, thereby unloading the head slider therefrom.
In general, the loading and unloading of the flying head slider is conducted in accordance with a predetermined speed profile, however on the other hand, the loading of the head slider is conducted on the magnetic disk, at an arbitrary position in the peripheral direction thereof. Then, for example, in Japanese Patent Laying-Open No. 2002-170349 (2002), for the purpose of increasing an area, on which data is recordable, by reducing the data recording inhibition area on the disk where the loading and unloading of the flying head slider is conducted, it is already known that an area is restricted only in a specific area on the disk, where the loading and unloading of this flying head slider are conducted. With this conventional art, the position is detected on the disk in the peripheral direction thereof, and in accordance with the position signal of peripheral direction, it is so controlled that the head slider loads on the predetermined position on the disk in the peripheral direction thereof.
However, in the case where loading/unloading of the head slider is conducted with using the load and unload mechanism of the conventional art mentioned above, there will occur contact and/or collision between the head slider and a surface of the magnetic disk. This is caused, for example, when the load and unload zone of the magnetic disk is injured by the contact with the head slider, thereby being convex-concave-like on the surface thereof, or due to this, the magnetic medium injured looses servo signals memorized thereon. In other words, according to the conventional art mentioned above, there will still occur a problem that the magnetic head is in contact with the convex-concave-like portion mentioned above, thereby being injured, and that the head runs away, out of control due to the loss of the servo signal recorded thereon.